F.Manson British Bomber Since 1914 (Putnam)

Air Department A.D.I Navyplane

It is sometimes said that Harold Bolas, in effect deputy chief designer at the Admiralty's Air Department, saw part of his job as exerting a restraining influence on the wilder excesses of his immediate senior, Harris Booth. Yet it should be remarked that, although most of Booth's own designs bordered on the grotesque, he was able to use his undoubted influence with the Board of Admiralty when it came to gaining official support for the designs of his subordinates (and he it was who strongly advised Murray Sueter to have such outstanding aeroplanes as the Handley Page O/100, and Sopwith 1 1/2-Strutter, Pup and Camel adopted by the Admiralty when they were still on the drawing board). It fell to Harold Bolas to initiate the design early in 1916 of a reconnaissance/bombing seaplane, officially designated the A.D.I, but generally referred to as the Navyplane. As the Air Department's Experimental Construction Depot at Port Victoria, Isle of Grain, was not yet fully equipped to undertake the building of complete aeroplanes, the initial A.D.I design was handed over to the Supermarine Aviation Works at Woolston, Southampton, for the detail design to be completed and construction of a prototype. Working in close collaboration with Bolas, Reginald Mitchell finished the necessary manufacturing drawings in an exceptionally short time, and the prototype, No 9095, was ready for testing by Cdr John Seddon in August. The A.D.I was a compact two-bay biplane whose two-man crew was accommodated in a finely-contoured lightweight monocoque nacelle located in the wing gap, the experimental air-cooled 150hp Smith Static radial engine driving a four-blade pusher propeller. Twin pontoon-type floats were braced to the nacelle and to the lower wings immediately below the inboard interplane struts. Twin fins and rudders were carried between two pairs of steel tubular tail booms, and the tailplane was mounted above the vertical surfaces. Twin tail floats, each with a water rudder, were attached beneath the lower pair of tail booms. The pilot occupied the rear cockpit, with the observer in the bow position. Two 100 lb bombs were to be carried under the wing centresection. The ten-cylinder Smith engine, brainchild of an American John W Smith, had evidently attracted the Admiralty's interest, and had shown promise during bench testing. A production order was placed with Heenan & Froude Ltd, but the engine never gave satisfactory performance in the few prototype aircraft in which it was flown. Little more was heard of the A.D.I until May 1917, when it re-appeared with by an A.R.I engine, designed by W O Bentley. However, although this engine displayed much improved reliability, the A.D.I's performance remained below that demanded by the Admiralty, and six further aircraft originally ordered were not built. Supermarine had made some efforts to continue development of an enlarged version of the A.D.I, called the Submarine Patrol Seaplane, powered by a 200hp engine, and submitted the design to the Air Board's Seaplane Specification N.3A. Although two prototypes were allotted the serial numbers N24 and N25, work on the project was discontinued when it was decided that the veteran Short Type 184 adequately met the requirements and would continue in service. (In any case the Supermarine aircraft would have been unable to lift the 1,100 lb 18 in torpedo, and did not possess folding wings - both requirements of N.3A.)

H.King Armament of British Aircraft (Putnam)

A.D. Navyplane. Built in 1916 for the same duties as the A.D. Flying Boat, the Navyplane twin-float seaplane had a pillar-mounted Lewis gun in the nose of the nacelle and provision for a small bomb load. In later years Maj T M. Barlow, who was well acquainted with this aircraft, with gun-mounting development generally, and with the Fairey "High-Speed" mounting in particular, said that the mounting was of 'movable, pivoted, traversing' type and was the 'forerunner of certain modern types'.

Jane's All The World Aircraft 1919

Pusher seaplane, built to Admiralty design, fitted with 130 h.p. Smith. This machine was completed and flying eight weeks after receipt of drawings. The nacelle is boat-built, with the lightest wooden construction known, the whole nacelle weighing 85 lbs.